Biomedical Engineering Reference

In-Depth Information

Fig. 6.7 Recorded and fitted forces (upper row) and accelerations (lower row) during a full

rotation of joint 4

0

@

1

A

ð
FT
T
V
V
Þ
1
c
F
x
ð
FT
T
IMU
A
Þ
x

f
g

F
user
¼

ð
FT
T
V
V
Þ
2
c
F
y
ð
FT
T
IMU
A
Þ
y

f
g

;

ð
6
:
11
Þ

and

ð
FT
T
V
V
Þ
3
c
F
z
ð
FT
T
IMU
A
Þ
z

f
g

0

1

ð
FT
T
V
V
Þ
4
c
M
x
ðð
FT
T
IMU
A
f
g
Þ
s
Þ
x

ð
FT
T
V
V
Þ
5
c
M
y
ðð
FT
T
IMU
A
f
g
Þ
s
Þ
y

ð
FT
T
V
V
Þ
6
c
M
z
ðð
FT
T
IMU
A
f
g
Þ
s
Þ
z

@

A

M
user
¼

ð
6
:
12
Þ

to estimate the gravity compensated forces F
user
and torques M
user
, based on the

voltage readings V, the accelerations A, and the tool's gravity force f
g
and centroid
s.

6.1.5 Data Acquisition for Evaluation of the FTA Sensor

In order to evaluate the FTA sensor's performance, we conduct a systematic

analysis starting with the estimation of the calibration error and stability. Subse-

quently, we test the accuracy of the gravity compensation based on accelerations.

Furthermore, we measure the latency of the FTA sensor which is important to

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